4x2 C24 Pressure Treated Timber Joist (47x100mm) - 3.6m

4x2 Treated Timber Joists measure 47x100mm (approx finished size of 45x95mm) and are 3.6m long. Made from responsibly sourced timber of high quality from FSC certified forests, these joists are kiln dried to ensure straightness and strength and treated for moisture and pest resistance.

• Conforms to BS 4978 and EN 14081:2006
• Kiln Dried for additional strength and durability
• Regularised for uniform size, with eased corners
• For use in exterior and structural applications
• Graded to C24 strength grade
• FSC Certified Timber

What is 4x2 Timber in mm?

Typically indicated in inches, the term "4x2" defines the joist size, (metric 47 x 100mm).  The regularisation process maintains uniformity along the timber's length, resulting in a "finished" size that is slightly smaller, generally around 45mm x 100mm, to ensure consistent dimensions throughout.

This slight variance is negligible and seldom affects most projects, remaining standard across 47x100, 4x2 regularised timber joists.

What are 4x2 C24 Timber Joists Used For?

A popular choice for constructing decks, garden buildings, and featuring prominently in the walls, roofs, and floors of timber-frame structures due to the strength, regularised 4x2 timber joists are one of the most widely used timber joist size. 

What is Regularised Timber?

Our timber joists are often referred to as “regularised” - meaning the lengths of timber are machine-finished to achieve a smooth finish and a uniform dimensions along the length of the timber joist. This can impact the finished size of the product by a few millimetres. The most common types of regularised timber joists are C16 and C24.

What Does Kiln Dried Mean?

Timber that is kiln dried is  placed in kilns where a consistent heat removes excess moisture from freshly cut boards, reducing weight, enhances strength and straightness, and improves its workability. Rather than using an air-drying process that can take several months to a year, kiln drying is a faster and more reliable method.

What Lengths Do 4x2 C24 Timber Joists Come in?

We provide both treated and untreated regularised 4x2 timber joists in a range of sizes: 2.4m, 3m, 3.6m, and 4.8m. While we strive to maintain stock across all sizes for delivery, there may be instances where we would supply a longer length as an alternative due to delay or unavailability of specific sizes in your region.

What Does C24 Stand For?

UK regularised timber is commonly categorised into two grades: C16 or C24. The "C" specifies the wood type: Conifer. The numerical value denotes the bend strength (determined by factors like imperfections and knots) C24 is the stronger grade of the two.

Typically, C16 timber joists are used in wall and roofing applications, while C24 is favoured for situations requiring exceptional strength, notably in roofing and flooring joists.

Do I Need Treated 4x2 Timber?

Opting for 4x2 treated timber is advisable for projects at risk of moisture or pest exposure. These timbers undergo pressure treatment, ensuring deep penetration of the treatment into the wood, providing durable protection against rot and pests. This selection is especially suitable for outdoor projects such as decking, roofing, and similar.